Der Bau der Erde

Abstract

THIS handsomely printed work, with a frontispiece, a folded map of general earth-structure, and line-illustrations in the text, is, in spite of its nominal price, a welcome sign of scientific recovery. The absence of an index is surely an accident which its well-known publishers will redress. Perhaps the most striking feature, and one that will encourage general use, is its crisp lucidity of style. We have selected at random ten consecutive sentences. They contain a total of 133 words, and one consists of six words only. This shows the German-Austrian language at its best, and we should like to attend Prof. Kober's lectures. His main thesis is that the building of folded mountain-chains is a process of “revolution ” following on one of “evolution,” In which geosynclinals have been formed. A geosynclinal represents what we sometimes regard as an epoch of quiescence. Its sinking base ultimately becomes nipped between two rigid masses of the lower crust, and the sedimentary accumulation rises in folds and overfolds at the surface. Mountain-building is the close of a cycle, and is a manifestation of the continuous contraction of the substance of the earth. A mountain-range denotes a lateral shrinkage of the outer crust. The portion of the earth that includes the geosynclinal masses and the resulting mountains is styled the “orogen”; the old and consolidated blocks are styled the “kratogen”—presumably because they exercise force upon the yielding orogen. All crust-disturbances originate in centripetal downward movement.

Der Bau der Erde.

By Prof. Leopold Kober. Pp. iv+324+2 plates. (Berlin: Gebrüder Borntraeger, 1921.) 80 marks.